Rocking piston pumps



Oct. 23, 1956 w. BAIER ROCKING PISTON PUMPS 7 Filed March 1'7, 1953 Inventor Wolfe r B aie' r- A-TTorn ay United States Patent O ROCKING PISTON PUMPS Walter Baier, Stockdorf, near Munich, Germany, assignor to Wilhelm Baier K. G., Stockdorf, near Munich, Germany, a firm Application March 17, 1953, Serial No. 342,919

Claims priority, application Germany March 17, 1950.

'1 Claim. (Cl. 103-159) This invention relates to improvements in rocking piston pumps.

Hitherto, rocking piston pumps have. been subject to several disadvantages. Primarily, since the control ports have normally been arranged radially with their orifices in the circumferential surface of the cylindrical portion of the rocker body, an efficient seal between this surface and the surface relative to which it moves cannot be attained. This disadvantage may partially be overcome by reducing the running clearance to a minimum by means of accurate machining, but this entails great expense, and only gives reasonably effective results until the moving parts become worn. Further, accurate machining of the rocker member itself is more difficult than machining of, for example, a plane surface and the control ports themselves cannot be formed sufliciently accurately, since the drilling must be started from the outer surface, and the tool removed at the moment when its tip has reached a predetermined position.

The present invention, as compared with known pumps, has a considerable advantage, in that the control ports are arranged perpendicular to a radius of the cylindrical portion of the rocker body (i. e. parallel to the axisabout which the rocker member pivots).

Since the control ports are thus no longer provided radially in the cylindrical portion of the rocker body, the body may be more efficiently supported and guided in the recess in which it moves. Known methods of guiding and supporting the rocker body have proved unsatisfactory, in the first place the guiding face is not closed, since in the upper portion the cylindrical space for the guiding of the eccentric overlaps it which in its rotary movement cuts into the circumferential cylindrical running face of the rocker body. On the side facing the eccentric the rocker body does not abut satisfactorily for the reason that seizing may occur, particularly during the suction stroke, due to the oil film being squeezed out of the bearing surface. Owing to the constant variation of the gap between the bearing surface and the rocker body moreover a pumping effect of this gap may be involved. Beyond this, the diameter of the bearing, and accordingly the friction opposing the rocking system is so great that the pump piston may even be deformed by this torque moment. Since the control apertures lie in a plane perpendicular to the cylindrical running face, the circumferential cylinder face need no longer serve for the journalling of the rocker body, and this journalling can be effected on a much smaller space, for example by a pivot pin. Thereby at the same time a further disadvantage of the usual rocking piston pumps is overcome. Owing to the large diameter of the bearing surfaces difliculties arose in these pumps with the use of different materials for the casing and the rocker body at changes of temperature because of different thermal expansions. This too, has now been overcome, since the play between the cylindrical running face and the rocker body can be made as large as desired. Preferably the bearing is arranged on the face opposite the control ports so that the frontal face of the rocker body can now be "ice machined flat in one operation. For the pressing-on of the rocker body against the front wall of the pump, which is provided with the control ports, preferably a spring arrangement is used, which consists for example of a leaf spring bearing on the rocker body by the intermediary of a ball. A pivot pin may be provided on both sides of the rocker body, one of which serves as a journal and theother as a guide pin for a coiled spring. If one journal pin only on the back of the rocker body is used, the frontal face of which is then completely plane, this pin may beprovided with a bore in which a compression spring is housed. A further advantage of the rocking piston pump according to the invention consists in that the rocker body need no longer be constructed crescent-shape with an almost closed outer cylindrical circumference, but can be reduced in size for the purpose of saving weight and material to such an extent that upon rocking to-and-fro the guidance required for the piston and the necessary closure of the control port concerned at any time is adequately. safeguarded.

A further advantage of the rocking piston pump according to the invention consists in that instead of using the piston proper for rocking the rocker body the ring mounted on the eccentric is provided with guide pins or is itself constructed as a double-armed guide pin. The wear of the piston can thus be reduced considerably which is of the greatest importance for an accurate output of the pumps. No bending moments whatever are transmitted to the pump piston and the same may be movably attached to the eccentric ring if desired. The guide pins may be dimensioned according to the strength required and their dimensions are not determined by output quantity and number of revolutions as are those of the piston.

In view of the even wear of the plane sealing face abut ting against the rocker body it is possible to make the individual pump components of different materials. For example for liquids hostile to lubricants such as petrol or the like, suitable materials can be used for the construction of the rocker body and of the other components. Bxamples of suitable materials are sintered metals, carbonmetal combinations such as used inter alia for the carbon brushes of electric motors, various artificial substances such as the products known under the trade names of nylon, Teflon or Styroflex.

In the accompanying drawings, one embodiment of the rocking piston pump according to the invention is illustrated by way of example.

Figure l is a section of a rocking piston pump according to the invention;

Figure 2 is an elevation of the cover plate, partly in section, of the rocking piston pump according to Figure 1;

Figure 3 is an elevation of the rocking piston pump with the cover plate removed;

Figure 4 is an elevation of a rocker body of reduced mass;

Figure 5 is a diagrammatic representation of the journalling of the rocker body in the pump casing, and

Figure 6 shows various embodiments of eccentric rings.

In the pump casing 1 the eccentric 4 is mounted on a shaft 3 journalled in a bushing 2 and on said eccentric 4 the eccentric ring 5 is mounted. On the shaft 3 a worm wheel 6 is fixed which is put into rotation by a driven worm 7. The shaft 3 is journalled on its other end at 8 in the cover plate 9. The eccentric 4 rotates within its eccentric ring 5 in a circular cylindrical recess 30 in the pump casing 1. This circular cylindrical recess overlaps with a circular cylindrical recess 11. In this recess 11 rocks the rocker body 12 which has a central bore 13 for the piston 14 which is attached to the eccentric ring 5. While in the usual rocking piston pumps the journalling of the rocker body was effected by the circumferential face of the cylindrical recess 11, the rocker body 12 according to the invention is provided with a pivot pirt 16 which. istjournalled in a bearing in the cover plate 9. At the lower end of the cylinder bore 13 for the piston 14 there is a transverse bore 17 which during the rocking to-and-fro of the rocker body 12 registers with a left hand side transverse bore 18 (Figure 2) and at the return movement registers with a right hand side transverse bore 19. These transverse bores 13 and 19 are in communication with the pressure and suction connectors, respectively, in the cover plate 9. The cover plate 9 is illustrated in Figure 2 in front elevation. There also the connectors 21 and 22 for the pressure and suction pipe line, respectively, will be seen, into which issue the transverse bores 18 and 19, respectively. The cover plate 9 is screwed on to the pump body 1 by means of screws 23. The rocker body 12 is pressed with its plane face against the plane sealing face of the cover plate 9 by a spring 24 which is housed in a recess 25 behind the cylindrical recess 11. The spring 24 has a hole in its centre and rests on a ball 26, which is journalled in a corresponding. recess 27 in the rocker body 12. The rocker body is thus always forced firmly against the cover plate 9 so that no liquid can leak out between rocker body and cover plate.

The rocker body illustrated in Figure is journalled in the pump casing 1 by means of a pivot pin 28 so that the plane frontal face of the rocker body 12 can be ground plane in one operation. in order to press the rocker body 12 firmly against the cover plate, the pivot pin 23 is provided with a bore in which a compression spring 28a is housed. Alternatively, pivot pins could be provided on both sides of the rocker body, the frontal pin serving as a journal pin and the rear pin as a guide pin for a coiled compression spring.

In Figure 4 is illustrated a particular embodiment of the rocker body which is reduced in weight by the recess 29, The width of the lower portion 30 is selected in such a manner that when the transverse bore 17 registerswith the transverse bore 18, the other transverse bore 19 is closed and vice versa. The components 31 and 32 serve for housing and guiding the eccentric ring 5.

In Figure 6 three dilterent embodiments of the eccentric ring are represented. The embodiment A is of the known kind, the piston 14 being attached below on the eccentric, ring 5 and effecting the rocking to-and-fro of the rocker body. in the embodiment B the eccentric ring 5 has guide pins 33 and 34 which slide in corresponding recesses in the rocker body 12. In the embodiment C these guide pins are shortened and may be integral with the eccentric ring. In the embodiments according to B and C it is possible to dimension the guide pins exclusively according to strength requirements. The pump piston isno longer stressed in bending and can be mounted movably on the eccentric ring, if desired. The wear of the pump piston is thereby reduced considerably, and the accuracy of the output is essentially improved.

When it is desired to pump liquids hostile to lubricants,

such as petrol or the like, by means of the rocking piston pump according to the invention, the rocker body 12 and the cover plate 9 can be made of suitable materials, if desired, such as sintered metals, carbon-metal combinations or artificial substances. Obviously when using the rocking piston pump according to the invention, for pumping liquids hostile to lubricants, lubrication of the journal pins 16 or 28 could be etfected alternatively by providing suitable grease lubricators of the type indicated at 20 and 2G in Fig. 1, consisting of a screw threadably engaged in a female thread of a cylindrical chamber 36 or 36 filled with a suitable consistent grease which can be forced into the bore of journal 16 or pin 8, respectively, by threading screw 20 or 20' into the chamber 36, or 36, respectively. Similarly, the journal points for the shaft 3 could be supplied with lubricant.

What I claim is:

An oscillating piston pump comprising a casing, a rocker mounted on an axis for oscillation in said casing and having a port issuing in a plane disposed at right angles to the axis of oscillation of the rocker and a pivot pin disposed concentrically to said axis of oscillation, a piston mounted for reciprocation in the rocker, an eccentric journalled in the casing for rotation about an axis spaced by a substantial distance from the axis of oscillation of the rocker, a ring engaging the eccentric by its inner annular surface and being jointedly connected to the piston, at least one guide bore in said rocker, rigid guiding means on said ring adapted to reciprocate parallel to the piston in said guide bore, whereby the piston is.

reciprocated in the rocker and the rocker simultaneously is oscillated in the casing which is closed on all sides except for an opening arranged in a plane disposed parallel and directly adjoining said rocker face in which said rocker port issues, and permitting insertion of the rocker, piston, and eccentric, and a cover plate adapted to be tightly connected to the open face of the casing and having admission and exhaust ports issuing in said rocker plane and alternately registering with the rocker port in the two extreme positions of the oscillating rocker, respectively.

References Cited in the file of this patent UNITED STATES PATENTS 1,088,608 Mitchell Feb. 24, 1914 1,675,546 Green July 3, 1928 1,693,323 Stecnstrup Nov. 27, 1928 1,944,198 Smith Jan. 23, 1934 2,619,039 Maisch Nov. 25, 1952 2,619,040 Maisch Nov. 25, 1952 2,653,756 Tveden Sept. 29, 1953 FOREIGN PATENTS 162,123 Great Britain Apr. 28, 1921 417,283 Great Britain c. Oct. 2, 1934 

